This is a continuation-in-part of my patent, Ser. No. 07/738,861, filed Aug. 8, 1991, which is a continuation of my patent Ser. No. 07/448,249, filed Dec. 12, 1989 now abandoned entitled "A Noninvasive Blood Glucose Measuring Device."
There are 11 million known diabetics in the United States. It is estimated that another 20 million people are predisposed to this disease while as many as 10 million diabetics may remain undiagnosed. Diabetes is a relentless disease, constantly degrading the person's health. Obesity is considered a major contributor to the disease rather than a symptom of it. Insulin from the body normally controls the level of blood sugar. However, in type 2 diabetes, the body's insulin is not effective and blood sugar levels rise too high. Complications of this effect can include kidney disease, blindness, and gangrene, which can require leg and foot amputations. Type 2 diabetes afflicts the vast majority of the nation's diabetics, according to the American Diabetes Association. The disease can often be controlled by diet and exercise only. This invention opens the door to more desirable and much closer control by the affected individual as well as easier scientific study of the disease at a level that hasn't been possible.
It has been said that no one ever dies of diabetes. It is common knowledge, however, that these persons live short lives with a multitude of health complications. Because control of this disease is an hour by hour health control problem for the diabetic, they must be made an informed partner in the maintenance of their health. This means that control of the disease is the primary responsibility of the diabetic patient with minimal supervision by health care specialists.
A major problem in treating one's own diabetes, is predicting accurately blood glucose level at different times of the day. An estimate is usually made, based on the results of a painful finger prick and blood tests, performed early each morning. The theory says that diet, exercise, and medication can each be juggled to accommodate the activities of a varying day based upon the daily test. Urine tape and tablet test methods for determining blood glucose are also on the market; however, these tests can be misleading if not performed frequently and require the privacy of a restroom. The prick test before morning insulin injection does not predict glucose level performance during the day and tests must be repeated often to obtain close blood sugar measurements. The pin prick test is painful, and so annoying that the information that a patient needs to properly control the disease may not be taken by the patient. The individual is then placed at higher risk to the ravages of the disease. Considering these various deficiencies in present blood glucose determination methods, a process is needed that measures glucose in a convenient manner in an easily obtained body fluid on a continuous basis to provide an indication of glucose concentration in the blood for the person wearing the device.
Briefly, in one preferred embodiment of the present invention, the proposed device will be an adhesive type patch appliance, consisting of a tick film battery, sensors for measuring glucose level in sweat or saliva, and indicators that present a visual bar chart of the wearer's blood sugar.
This invention covers the need to simultaneously measure and indicate glucose concentration in the blood on a continuous basis to allow a diabetic person to be aware of the glucose level in their blood or the control achieved over the disease at any time of the day. With continuous knowledge of blood glucose levels, modifications can be made by the patient as to diet, exercise, or antidiabetes medication, to control and greatly delay the consequences of the disease.
This patent relates to a noninvasive sensing, measuring, and indicating device for blood glucose measurement. The device produces real-time indication of the glucose concentration in sweat, this concentration has been found to be approximately 1% of the glucose level in the blood. The device allows enzymatic and electrochemical reactions to occur uniformly with a sweat-moving wick operating to move sweat past a sensing device. Glucose level is quantified with a bridge system that compares oxygen in sweat with residual oxygen in sweat after a portion of sweat reacts with a glucose oxidizing enzyme. The system is comprised of electronic circuitry with a battery, sensors and a reference sensor, and electrochemical indicator and a sweatmoving wick. In one embodiment, the system or unit operates to automatically indicate ascending and descending glucose levels over the course of a day by virtue of plating action to cause visible bars to change color. This embodiment covers a low cost, disposable unit that will result in a body worn, direct reading glucose meter as an alternative to other more bothersome blood sugar tests.
An advantage of the present invention is that it provides a more desireable method for the wearer to quickly check and correct a low blood glucose condition with the ingestion of candy, before the onset of unconsciousness or diabetic coma. Additional benefit to emergency health care specialists when responding to a comatized patient wearing the device, will be realized by their understanding of the condition of the patient by the visual read out on the unit.
Still another advantage of the present invention will be the potential to improve the health of 4% of this nation's populations (diabetics); providing them with more information for the control of this disease will equate to lower health maintenance costs. The device may also provide an effective method of public screening for diabetics by handing out the devices free of charge to detect the disease at earlier stages when treatment and control is more effective.
Another advantage of the present invention is to provide a more desireable method of determining blood glucose without the requirement of drawing blood. However, the method of drawing blood may be used to calibrate the body worn display instrument from time to time.
Still another feature of the present development is to provide an assembly for connecting a number of sensors and continuous indicators as a packaged electronic circuit in such a manner that the total assembly occupies a small area on the skin or body of the person.
Another feature of the present invention is to provide a sealed conducting means or capillary means to move sweat from the body, past the sensors for blood glucose level determination and on to be evaporated regardless of the glucose concentration in the sweat of the person wearing the device.
Another feature of the present invention is to provide a method of constantly determining blood glucose so that by anti-diabetes medication, diet, and exercise, a person wearing the device can keep blood glucose within the levels safe for health.
Still another feature of the present development is to provide a manufacturing method that will allow automation and production of a measuring device that otherwise requires time consuming, costly, manual methods of determination of blood glucose level. Presently, much of the blood glucose analysis is deferred by the patient because of inconvenience and cost with a resulting decrease in the diabetic's health.
Briefly, these and other features and advantages are accomplished in one preferred embodiment of the present development by an assembly which includes a conductive ciruit drawn or printed on a preform, glucose sensors, a reference sensor, a wick that acts as a sweat pump and a battery; all in a form designed to have an operating life of 18 hours or more after activation, producing measurement and indication of blood glucose levels consistent with that obtained by blood samples.
T. C. Boysen, Shigeree Yanagaun, Fusaho Sato and Uingo Sato in a paper published in 1984 in the Journal of Applied Psychology described a modified method for sweat collection and in this paper they also showed that two different people each had a glucose concentration in blood plasma of about 100 mg/dl or 1000 ppm before ingestion of a large amount of glucose. Subject A had approximately 1 ppm glucose in his perspiration while the other, subject B, had approximately 6 ppm glucose in his perspiration. After ingestion of glucose, both A and B had approximately 3500 ppm glucose in the blood plasma but in less than 5 minutes, glucose in the blood plasma of B had dropped to approximately 3000 ppm, while glucose in blood plasma of A had dropped to less than 2000 ppm. At the same time, glucose in perspiration from subject B rose to over 10 ppm and glucose in perspiration from subject A rose to over 3 ppm.
This data indicates that our device to measure glucose in perspiration must be calibrated for each person. The data also indicates a correlation between changes in glucose in blood plasma and glucose in perspiration. Thus a user of the invention would calibrate the output signal against the usual blood measurement of glucose.
There are several embodiments of the invention that will be more fully described in the following pages.